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SARS‐CoV‐2 infection is causing a pandemic disease that is reflected in challenging public health problems worldwide. HLA‐based epitope prediction and its association with disease outcomes provide an important base for treatment design. A bioinformatic prediction of T cell epitopes and their restricted HLA class I and II alleles was performed to obtain immunogenic epitopes and HLA alleles from the spike protein of the SARS‐CoV‐2 virus. Also, a correlation with the predicted fatality rate of hospitalized patients in 28 states of Mexico was done. Here, we describe a set of ten highly immunogenic epitopes, together with different HLA alleles that can efficiently present these epitopes to T cells. Most of these epitopes are located within the S1 subunit of the spike protein, suggesting that this area is highly immunogenic. A statistical negative correlation was found between the frequency of HLA‐DRB1*01 and the fatality rate in hospitalized patients in Mexico. This article is protected by copyright. All rights reserved.

Systemic Lupus Erythematosus (SLE) is an autoimmune inflammatory disorder for which Major Histocompatibility Complex (MHC) genes are well identified as risk factors. SLE patients present different clinical phenotypes, which are partly explained by admixture patterns variation among Mexicans. Population genetic has insight into the high genetic variability of Mexicans, mainly described through HLA gene studies with anthropological and biomedical importance. A prospective, case-control study was performed. In this study, we recruited 146 SLE patients, and 234 healthy individuals were included as a control group; both groups were admixed Mexicans from Mexico City. The HLA typing methods were based on Next Generation Sequencing and Sequence-Based Typing (SBT). The data analysis was performed with population genetic programs and statistical packages. The admixture estimations based on HLA-B and -DRB1 revealed that SLE patients have a higher Southwestern European ancestry proportion (48 ± 8%) than healthy individuals (30 ± 7%). In contrast, Mexican Native American components are diminished in SLE patients (44 ± 1%) and augmented in Healthy individuals (63 ± 4%). HLA alleles and haplotypes’ frequency analysis found variants previously described in SLE patients from Mexico City. Moreover, a conserved extended haplotype that confers risk to develop SLE was found, the HLA-A∗29:02∼C∗16:01∼B∗44:03∼DRB1∗07:01∼DQB1∗02:02, pC = 0.02, OR = 1.41. Consistent with the admixture estimations, the origin of all risk alleles and haplotypes found in this study are European, while the protection alleles are Mexican Native American. The analysis of genetic distances supported that the SLE patient group is closer to the Southwestern European parental populace and farthest from Mexican Native Americans than healthy individuals. Heterogeneity of genetic admixture determines SLE susceptibility and protection in Mexicans. HLA sequencing is helpful to determine susceptibility alleles and haplotypes restricted to some populations.

SUMMARY Percent germination and length of hyphae of germinated Glomus mosseae spores, cultivated on water agar, decreased significantly in the presence of Aspergillus niger; this decrease was independent of any change in pH of the medium. Soluble and volatile compounds produced by A. niger significantly decreased percentage spore germination and the hyphal length of G. mosseae on water agar. The decrease caused by volatile compounds was significantly greater when A. niger was grown on malt extract agar. Shoot dry weights of maize and lettuce plants cultivated in soil in pots, and percentage arbuscular mycorrhizal (AM) root colonization of plants grown either in sand: vermiculite tubes inoculated with G. mosseae spores or in soil in pots with soil inoculum, were unaffected by A. niger when this saprobe was inoculated 2 wk after G. mosseae. Shoot dry weights and percentage AM colonization of plants decreased when the saprobic fungus was inoculated at the same time or 2 wk before G. mosseae. However, the metabolic activity resulting from AM colonization, measured as the percentage of mycelium showing succinate dehydrogenase activity, decreased in all treatments. The population of A. niger decreased when inoculated to the rhizosphere of plants at the same time as, or 2 wk after, G. mosseae, but not when it was inoculated 2 wk before G. mosseae. Our results show that G. mosseae decreases the saprobic fungal population through its effect on the plant, whereas A. niger, by the production of soluble or volatile substances, inhibits G. mosseae in its extramatrical stage.

The true myrtle, Myrtus communis, is a small perennial evergreen tree that occurs in Europe, Africa, and Asia with a circum-Mediterranean geographic distribution. Unfortunately, the Mediterranean Forests, where M. communis occurs, are critically endangered and are currently restricted to small fragmented areas in protected conservation units. In the present work, we performed, for the first time, a metabarcoding study on the spatial variation of fungal community structure in the foliar endophytome of this endemic plant of the Mediterranean biome, using bipartite network analysis as a model. The local bipartite network of Myrtus communis individuals and their foliar endophytic fungi is very low connected, with low nestedness, and moderately high specialization and modularity. Similar network patterns were also retrieved in both culture-dependent and amplicon metagenomics of foliar endophytes in distinct arboreal hosts in varied biomes. Furthermore, the majority of putative fungal endophytes species were basidiomycete woody saprotrophs of the orders Polyporales, Agaricales, and Hymenochaetales. Altogether, these findings suggest a possible adaptation of these wood-decaying fungi to cope with moisture limitation and spatial scarcity of their primary substrate (dead wood), which are totally consistent with the predictions of the viaphytism hypothesis that wood-decomposing fungi inhabit the internal leaf tissue of forest trees in order to enhance dispersal to substrates on the forest floor, by using leaves as vectors and as refugia, during periods of environmental stress., Comissión Interministerial de Ciencia y Tecnología (CICYT): AGL2008-00572. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: 2330-10-5/CAPES. CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil). Consejo Superior de Investigaciones Científicas (CSIC) and the European Social Funds.

To evaluate the association of C-reactive protein (CRP) polymorphisms with risk of development SLE in a group of Mexican individuals. Five CRP polymorphisms (rs3093059, rs3093062, rs1800947, rs1130864, and rs1205) were determined by PCR-restriction fragment length polymorphism and SNP rs3093061 by refractory mutation system PCR assay in 126 SLE patients and 131 controls. Four of the polymorphisms showed differences between patients and controls. rs3093061 polymorphism was associated with a lower risk of developing lupus principally in the codominant 2 (OR = 0.219, 95% CI 0.108-0.785, P = 0.015) model. rs1130864 was associated with decreased risk mainly under codominant 1 (OR = 0.288, 95% CI 0.143-0.581, P = 0.001) model. rs1205 was associated under the over-dominant model (OR = 0.504, 95% CI 0.270-0.942, P = 0.032). The rs3091244 polymorphism was associated with decreased risk of SLE mostly under additive (OR = 0.605, 95% CI 0.393-0.931. P = 0.022) model. Our study establishes that rs3093061, rs1130864, rs1205, and rs3091244 polymorphisms are associated with decreased risk of developing SLE.

The use of “alpeorujo” (dry olive residue) has been proposed as an organic amendment in order to enhance soil structure and to increase C storage in soils. The aim of this work is to study how aqueous alpeorujo (ADOR) extracts bioremediated with white-rot fungi and three representative phenolic acids present in this extract (protocatechuic, vanillic and caffeic acid) affect the growth of the arbuscular mychorrhizal fungus Rhizophagus custos in monoxenic culture. Our results show that ADOR decreased mycorrhization parameters; however, this negative effect ceased after ADOR bioremediation. Although protocatechuic and vanillic acids have drastic negative effects at high concentrations, these phenols enhance mycorrhization processes at low concentrations and caffeic acid negatively affects symbiosis at low concentrations. Finally, the capacity of root biomass to dissipate individual phenols was also estimated, in which mycorrhized roots improve phenol dissipation in the growth medium in the presence of different phenols. This study highlights the important role played by arbuscular mycorrhiza in protecting plants from phytotoxicity., This study was carried out thanks to financial support from the Ministry of Economy and Competitiveness (MINECO) within the framework of project AGL2012-32873. R. Reina gratefully acknowledges the support provided by the JAE-Pre Program which is co-financed by CSIC and the European Social Fund. E. Aranda thanks the Ministry of Economy and Competitiveness (MINECO) and FEDER funds for co-funding the Ramón y Cajal contract (RYC-2013-12481).

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disorder for which Major Histocompatibility Complex (MHC) genes are well-identified as risk factors. SLE patients have different phenotypes or clinical presentations, which vary among Mexicans. This variation could be explained by ethnicity and admixture. Since socioeconomic status probably limits and change the patterns of migration, this factor could favor inbreeding and homogamy in some geographic areas. Consequently, it could alter or restrict the possibilities of admixture too. Therefore, the socioeconomic status may also have implications in the susceptibility and the clinical heterogeneity of SLE in Mexican patients.One hundred twenty-three SLE patients and 234 healthy individuals with Mexican admixed ancestry were recruited. HLA alleles were analyzed using the HLA typing method based on Sequence-based typing (SBT).As expected, it was found an increased frequency of the HLA-DRB1*03:01 allele in all socioeconomic groups when compared with healthy individuals. The susceptibility allele found in the low-income SLE patients was HLA-DRB1*04:05 whereas, the susceptibility alleles for the high-income SLE patients were HLA-DRB1*07:01 (pC = 0.03, OR = 2.0) and HLA-DRB1*11:04 (pC = 0.0004, OR = 5.1). Additionally, the frequencies of two protective alleles HLA-DRB1*14:06 (pC = 0.01, OR = 0.28) and HLA-DRB1*16:02 (pC = 0.04, OR = 0.22) were found diminished. These findings correlate with the admixture differences between low-income and high-income SLE patients. The clinical manifestations showed a different distribution between both groups. Arthritis and neurological disorder were prevalent in low-income SLE patients, while the hematological disorder was prevalent in high-income SLE patients.These findings suggest that HLA class II DRB1 genes contribute to the susceptibility and protection to develop SLE differently depending on socioeconomic status. Due to this, the clinical manifestations vary among patients and it could be related to different admixture charge.Key Point• HLA class II DRB1 genes contribute to the susceptibility and protection to develop SLE differently depending on socioeconomic status.

Accumulation of heavy metals in soil causes loss of cover vegetation and increases the production of reactive oxygen species (ROS). ROS accumulation induces the expression of genes encoding antioxidant enzymes and other proteins involved in redox homeostasis. This study aimed to evaluate the interaction between a saprophytic fungal consortium and mycorrhizal Rhizophagus irregularis with regard to the oxidative stress and molecular responses of Solanum lycopersicum L. grown in a soil contaminated with heavy metals. We determined the effects of the saprophytic fungal consortium (Bjerkandera adusta and Mortierella sp) and the mycorrhizal fungus Rhizophagus irregularis on the plant antioxidant response and the expression levels of genes encoding metallothioneins (MT), phytochelatins (PC), the NRAMP transporter and heat shock protein (HSP) in Solanum lycopersicum cultivated in a heavy metal-contaminated soil. The fungal consortium increased plant growth, and the co-inoculation with R. irregularis synergistically improved soil biochemical activities. Superoxide dismutase activity decreased in all treatments. Peroxidase activity (ascorbate and guaiacol) increased in plants inoculated with R. irregularis and the fungal consortium. Dual inoculation decreased the malondialdehyde content in the leaves and increased transcription of the NRAMP, GR, MT2b, PCS and HSP90 genes. Our results demonstrate that co-inoculation contributes to reduced plant stress by improving defence mechanisms and homeostasis

Phosphorus is one of the most important macronutrients required for plant growth. Plants have evolved many strategies for inorganic phosphorus (Pi) acquisition, including the symbiotic pathways, involving the formation of mycorrhiza. With regard to arbuscular mycorrhiza (AM), high Pi availability has long been known to negatively affect this association, although the underlying mechanism is unknown. In the present study, the interactive role played by ethylene and Pi in AM regulation was investigated in the tomato-Rhizophagus irregularis symbiosis. AM fungal colonization was analysed in epi, rin and NRO ethylene-responsive mutants under different Pi availability conditions, with a focus on the late stages of the interaction. Although Pi inhibited mycorrhizal parameters in the ethylene-insensitive rin mutant and wild-type cultivars, it did not alter the mycorrhization of the epi tomato mutant, which exhibits a constitutive ethylene-induced response. As with the colonization parameters, root ethylene content and the expression of AM-related and ethylene receptor 6 genes were inhibited by Pi in wild-type cultivars and rin mutants, but were unaffected or slightly activated in epi plants. The application of ethephon offsets the negative impact on the mycorrhizal development caused by the application of Pi. This compensation effect is dose dependent and was ineffective in the NRO mutant, which is more insensitive to the action of ethylene. Our results provide evidence that ethylene signalling negatively affects the suppressive effect of Pi on AM formation and suggests an overlap between this suppressive effect and the regulatory mechanism of Pi-starvation response pathway in plants mediated by ethylene., This study was supported by grants from the Comisión Interministerial de Ciencia y Tecnología (CICYT) and the European Regional Development Fund (ERDF) through the Ministerio de Economía y Competitividad in Spain (AGL2011-25930; AGL2014-52298-P) as well as the Junta de Andalucía (Research Group BIO 260). We wish to thank the Tomato Genetics Resource Centre (TGRC) of the University of California for providing tomato seeds. We would also like to thank Michael O’Shea for proof-reading the document. R Torres de los Santos was supported by the Carolina foundation.

Arbuscular mycorrhizal fungi (AMF) establish an obligate mutualistic symbiosis with many plant species, increasing the uptake of phosphorous and other low-mobile nutrients by roots. In addition, AMF improve biotic and abiotic stress tolerance of host plants. Under these conditions, reactive oxygen species (ROS) increase occasional damage to proteins, lipids and DNA. Antioxidative enzymes in plants can play an important role in detoxifying ROS, thereby alleviating oxidative stress. In nursery practices, plants are subjected at least to two transplant conditions before being transplanted outside. It is important to achieve an optimal plant size to withstand environmental or other stresses when plants are transplanted into the field. The transplantation process can be considered a stress because plants have to adapt to new abiotic and biotic (rhizospheric) conditions. The aim of this study was to evaluate the effect of two Rhizophagus intraradices (N.C. Schenck & G.S. Sm.) C. Walker & A. Schüßler strains, GA5 and GC2, single and co-inoculated under two-transplant soil conditions, sterile and non-sterile, using cuttings of pomegranate (Punica granatum L.) as a model plant. These results showed that the GA5 single strain-inoculated plants improved growth and antioxidative enzyme responses to two transplant stress conditions. In conclusion, early mycorrhizal inoculation generates healthy plants that are more protected against environmental conditions, thereby improving plant transplant stress tolerance., The authors thank Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Agencia Nacional de Promoción Científica y Tecnológica (ANCyPT) and Universidad de Buenos Aires (UBA) for financial support.

espanolObjetivo: Se investigo la proporcion de la expresion genica del receptor variable beta de celulas T (Vβ TCR) en linfocitos perifericos CD3+ en pacientes con lupus eritematoso generalizado (LEG) familiar y no familiar. Metodo: El repertorio de Vβ TCR se estudio en 14 familias que presentaban mas de un miembro con LEG. El uso de Vβ TCR en pacientes con LEG (n = 27) se comparo con el de los miembros sanos de estas familias (n = 47), con 37 pacientes con LEG esporadico y con 15 controles sanos. La expresion del repertorio de Vβ TCR se estudio por citometria de flujo multiparametrica utilizando un arreglo de 24 diferentes anticuerpos monoclonales especificos de genes familiares para Vβ TCR. Resultados: Se encontro el mismo perfil de expresion en las comparaciones entre los casos de LEG esporadico y familiar, asi como en los consanguineos sanos de las familias multicasos, que incluia una expresion incrementada de Vβ 5.2, Vβ 11 y Vβ 16, y una menor expresion de Vβ 3, Vβ4, Vβ 7.1 y Vβ 7. De manera interesante, solo Vβ 17 se expreso de modo diferente entre casos familiares y esporadicos de LEG. Igualmente, la expresion incrementada de Vβ 9 fue el distintivo entre los casos de LEG familiar (casos y consanguineos sanos) y los controles sanos. Conclusiones: Estos resultados refuerzan la nocion de que el perfil final del repertorio Vβ TCR observado en LEG familiar y no familiar parece surgir de la interaccion de factores geneticos, ambientales e inmunorreguladores, ademas de que pueden explicar las alteraciones inmunitarias que se observan en los consanguineos sanos de pacientes con LEG. EnglishObjective: We investigated the proportion of Vβ T cell receptor (TCR) gene expression in peripheral CD3+ lymphocytes in familial and non-familial systemic lupus erythematosus (SLE) patients. Method: The Vβ TCR repertoire was studied in 14 families in which several members had SLE. The Vβ TCR usage in SLE patients (n = 27) was compared with that in healthy members of these multiplex families (n = 47), in 37 sporadic SLE patients who had no relatives with SLE, and in 15 healthy unrelated controls. Vβ TCR repertoire expression was studied by multiparameter flow cytometry with the use of an array of 24 different Vβ TCR gene family-specific monoclonal antibodies. Results: We found the same Vβ TCR expression profile in the comparisons between sporadic SLE and familial SLE cases and healthy relatives, which included increased expression of Vβ 5.2, Vβ 11 and Vβ 16, and lower expression of Vβ 3, Vβ 4, Vβ 7.1 and Vβ 17. Interestingly, solely Vβ 17 was differentially expressed among sporadic and familial SLE. Also, increased expression of Vβ 9 was the hallmark among familial SLE (cases and healthy relatives) in comparison to controls. Conclusion: These results highlight the notion that the final profile of the Vβ TCR repertoire seen in familial and non-familial SLE seems to arise from the interaction of genetic, environmental, and immunoregulatory factors. Furthermore, it may contribute to the immunologic abnormalities affecting relatives of SLE patients.

Background Solanum lycopersicum, an economically important crop grown worldwide, has been used as a model for the study of arbuscular mycorrhizal (AM) symbiosis in non-legume plants for several years and several cDNA array hybridization studies have revealed specific transcriptomic profiles of mycorrhizal tomato roots. However, a method to easily screen candidate genes which could play an important role during tomato mycorrhization is required. Results We have developed an optimized procedure for composite tomato plant obtaining achieved through Agrobacterium rhizogenes-mediated transformation. This protocol involves the unusual in vitro culture of composite plants between two filter papers placed on the culture media. In addition, we show that DsRed is an appropriate molecular marker for the precise selection of cotransformed tomato hairy roots. S. lycopersicum composite plant hairy roots appear to be colonized by the AM fungus Rhizophagus irregularis in a manner similar to that of normal roots, and a modified construct useful for localizing the expression of promoters putatively associated with mycorrhization was developed and tested. Conclusions In this study, we present an easy, fast and low-cost procedure to study AM symbiosis in tomato roots., This study was funded by grants from the Interministerial Commission of Science and Technology (CICYT) and the European Regional Development Fund (FEDER) through the Ministry of Economy, Industry and Competitiveness in Spain (AGL2014-52298-P). Tania Ho’s research fellowship was supported by the FPI-MINECO program. We are grateful to Dr. M Udvardi (Noble Research Institute) for generously providing the pUBIcGFP-DR vector. We also thank Dr. JA López-Ráez and Dr. A. Belver from the EEZ-CSIC for their help and critical comments; and M. Calvo-Polanco for encouraging us to publish this protocol. We also wish to thank Michael O’Shea for proof-reading the document.

The effect of the dual inoculation with arbuscular mycorrhizal (AM) and saprophytic fungi and a combination of wheat straw and sewage sludge residues were studied by determining their effect on dry weight of tomato and on chemical and biochemical properties of soil. Incubation of organic residue (sewage sludge combined with wheat straw) with saprophytic fungi and plant inoculation with mycorrhizal fungi was essential to study plant growth promotion. Soil application of organic residues increased the dry weight of tomato inoculated with Rhizophagus irregularis. The greatest shoot dry mass was obtained when the organic residues were incubated with Trichoderma harzianum and applied to AM plants. However, the greatest percentage of root length colonized with AM in the presence of the organic residues was obtained with inoculation with Coriolopsis rigida. The relative chlorophyll was greatest in mycorrhizal plants regardless of the presence of either saprophytic fungus. The presence of the saprophytic fungi increased soil pH as the incubation time increased. Soil nitrogen and phosphorus contents and acid phosphatase were stimulated by the addition of organic residues, and contents of N and P. Total N and P content in soil increased when the organic residue was incubated with saprobe fungi, but this effect decreased as the incubation period of the residue with saprobe fungi increased. The same trend was observed for soil β-glucosidase and fluorescein diacetate activities. The application of organic residues in the presence of AM and saprophytic fungi seems to be an interesting option as a biofertilizer to improve plant growth and biochemical parameters of soils.

Dry olive residue (DOR), a solid by-product of the two-phase olive oil extraction system, is rich in organic matter and nutritionally important compounds. However, the agronomic application of this residue may impact negatively on the soil ecosystem due to its toxic components. The aim of the present study was to investigate the impact of raw DOR, Coriolopsis floccosa-transformed DOR and Fusarium oxysporumtransformed DOR on soil biological properties. To do this, soil enzyme activities, fungal community size (quantitative PCR) and fungal community structure (DGGE of 18S rRNA gene) were measured. The impact of biotransformed and nonbiotransformed DOR applications to soil depended on two factors: the variable sensitivity of the soil to the residue?s composition and the duration of exposure to amendments. The application of this biotransformed residue enhanced soil enzyme activities (phosphatase, b-glucosidase and urease) with respect to soil amended with nonbiotransformed residue. The quantification of the 18S rRNA gene copy number indicated that the different amendments stimulated relative abundance. DGGE analysis showed that the amendments produced changes in fungal community structure although variations in fungal diversity were only detected after C. floccosa-transformed DOR addition at 60 days, probably due to the enhancement of species such as Chaetomium globosum and Chalazion helveticum. Fil: Siles, José A.. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Perez Mendoza, Daniel. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Ibañez, José A.. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Scervino, Jose Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Ocampo, Juan A.. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Garcia Romera, Inmaculada. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Sampedro, Inmaculada. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España. Dartmouth College; Estados Unidos

The behaviour of tomato plants inoculated with arbuscular mycorrhizal (AM) fungi grown in the presence of aqueous extracts from dry olive residue (ADOR) was studied in order to understand how this symbiotic relationship helps plants to cope with oxidative stress caused by ADOR. The influence of AM symbiosis on plant growth and other physiological parameters was also studied. Tomato plants were inoculated with the AM fungus Funneliformis mosseae and were grown in the presence of ADOR bioremediated and non-bioremediated by Coriolopsis floccosa and Penicillium chrysogenum-10. The antioxidant response as well as parameters of oxidative damage were examined in roots and leaves. The data showed a significant increase in the biomass of AM plant growth in the presence of ADOR, regardless of whether it was bioremediated. The establishment and development of the symbiosis were negatively affected after plants were exposed to ADOR. No differences were observed in the relative water content (RWC) or PS II efficiency between non-AM and AM plants. The increase in the enzymatic activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and glutathione-S-transferase (GST; EC 2.5.1.18) were simultaneous to the reduction of MDA levels and H2O2 content in AM root growth in the presence of ADOR. Similar H2O2 levels were observed among non-AM and AM plants, although only AM plants showed reduced lipid peroxidation content, probably due to the involvement of antioxidant enzymes. The results highlight how the application of both bioremediated ADOR and AM fungi can alleviate the oxidative stress conditions, improving the growth and development of tomato plants.

The single application of either sewage sludge with high aluminium concentration, wheat straw or the mixture of both residues to soil did not increase the growth of Eucalyptus globulus Labill. However, inoculation with either the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis, the saprobe fungi Coriolopsis rigida (Berk. Et Mont.) Murrill and Phanerochaete chrysosporium Burds or the combination of each saprobe with the AM fungus increased both the P concentration and dry weight of E. globulus shoots. These effects were greater in the presence of wheat straw or sewage sludge, but were greatest in the presence of the mixed residue. Phanerochaete chrysosporium had the greatest effect on plant dry weight when co-inoculated with R. irregularis in the treatment with mixed residue. The co-inoculation of AM and saprobe fungi increased fluorescein diacetate and β-glucosidase activities in the bulk soil of E. globulus grown in the treatment with mixed residue. However, only the AM fungus increased dehydr...

The in vivo conversion of dry olive mill residue (DOR) by wood- and dung-dwelling fungi - Auricularia auricula-judae, Bjerkandera adusta and Coprinellus radians - increases peroxidase secretion up to 3.2-3.5-fold (∼1.3, 3.5 and 7.0 Ug(-1) DOR for dye-decolorizing peroxidase, manganese peroxidase and aromatic peroxygenases, respectively). The incubation of DOR with these fungi produced a sharp decrease in total phenolic content (100% within 4 wk), a reduction in phytotoxicity as well as a certain degree of plant growth caused by the stimulating effect of fungal-treated DOR. These findings correlate with a characteristic shift in the fragmentation pattern of water-soluble aromatics (detected at 280 nm) from low (0.2, 1.5 and 2.2 kDa, respectively) to high molecular mass (35 to >200 kDa), which demonstrates the presence of a polymerization process. Phenol-rich agricultural residues are a useful tool for enzyme expression and production studies of peroxidase-producing Agaricomycetes which could make DOR a valuable organic fertilizer.

The water regime affects a wide variety of physiological and biochemical processes in plants including an increased production of reactive oxygen species (ROS) capable of causing oxidative damage to proteins, DNA and lipids. Arbuscular mycorrhizal fungi (AMF) colonize a wide range of plant species though the ability of different AMF species to promote host growth or contribute to plant water deficit resistance varies. The first phase of olive tree cultivation takes place in a nursery where plants usually suffer stress by drying. Currently, olive production systems do not use of AMF to counteract this problem. To study the colonization strategies of two AMF strains and their efficiency with respect to growth and their effect on enzymatic activities, we inoculated them individually and co-inoculated then on olive plants under nursery growing conditions. The results showed the benefits generated by these fungi in terms of growth and survival rate. Co-inoculation, particularly, improved growth and reduced the damage due to water stress, partly as a result of the activation of the antioxidant defenses in the olive plant host. Fil: Bompadre, Maria Josefina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Microbiologia del Suelo; Argentina Fil: Rios, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Colombo, Roxana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Microbiologia del Suelo; Argentina Fil: Fernandez Bidondo, Laura. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Microbiologia del Suelo; Argentina Fil: Silvani, Vanesa Analia. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Microbiologia del Suelo; Argentina Fil: Pardo, Alejandro Guillermo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Laboratorio de Micologia Molecular; Argentina Fil: Ocampo, Juan Antonio. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidin; España Fil: Godeas, Alicia Margarita. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Microbiologia del Suelo; Argentina

The establishment of an Arbuscular Mycorrhizal symbiotic interaction (MA) is a successful strategy to substantially promote plant growth, development and fitness. Numerous studies have supported the hypothesis that plant hormones play an important role in the recognition and establishment of symbiosis. Particular attention has been devoted to jasmonic acid (JA) and its derivates, the jasmonates, which are believed to play a major role in AM symbiosis. Jasmonates belong to a diverse class of lipid metabolites known as oxylipins that include other biologically active molecules. Recent transcriptional analyses revealed upregulation of the oxylipin pathway during AM symbiosis in mycorrhizal tomato roots and point a key regulatory feature for oxylipins during AM symbiosis in tomato, particularly these derived from the action of 9-lipoxygenases (9-LOX). In this mini-review we highlight recent progress understanding the function of oxylipins in the establishment of the AM symbiosis and hypothesize that the activation of the 9-LOX pathway might be part of the activation of host defense responses which will then contribute to both, the control of AM fungal spread and the increased resistance to fungal pathogens in mycorrhizal plants.

Plant hormones have become appropriate candidates for driving functional plant mycorrhization programs, including the processes that regulate the formation of arbuscules in arbuscular mycorrhizal (AM) symbiosis. Here, we examine the role played by ABA/GA interactions regulating the formation of AM in tomato. We report differences in ABA and GA metabolism between control and mycorrhizal roots. Active synthesis and catabolism of ABA occur in AM roots. GAs level increases as a consequence of a symbiosis-induced mechanism that requires functional arbuscules which in turn is dependent on a functional ABA pathway. A negative interaction in their metabolism has been demonstrated. ABA attenuates GA-biosynthetic and increases GA-catabolic gene expression leading to a reduction in bioactive GAs. Vice versa, GA activated ABA catabolism mainly in mycorrhizal roots. The negative impact of GA3 on arbuscule abundance in wild-type plants is partially offset by treatment with ABA and the application of a GA biosynthesis inhibitor rescued the arbuscule abundance in the ABA-deficient sitiens mutant. These findings, coupled with the evidence that ABA application leads to reduce bioactive GA1, support the hypothesis that ABA could act modifying bioactive GA level to regulate AM. Taken together, our results suggest that these hormones perform essential functions and antagonize each other by oppositely regulating AM formation in tomato roots., This study was supported by grants from the Comisión Interministerial de Ciencia y Tecnología (CICYT) and Fondos Europeos de Desarrollo Regional (FEDER) through the Ministerio de Economía y Competitividad in Spain (AGL2008-00742; AGL2011-25930) as well as the Junta de Andalucía (Research Group BIO 260). JM-R was supported by a research fellowship from the FPU-MICINN program. The work on hormone measurements was funded by a Grant Agency of the Czech Republic (grant no. 14-34792S) and by the Ministry of Education, Youth and Sports of the Czech Republic through the National Program for Sustainability I (Nr. LO1204).

Micromonospora is a Gram-positive bacterium that can be isolated from nitrogen-fixing root nodules from healthy leguminous plants and promotes plant growth. Selected strains of Micromonospora isolated in our laboratory from alfalfa root nodules showed in vitro antifungal activity against several pathogenic fungi. Moreover, root inoculation of tomato plants with these Micromonospora strains effectively reduced leaf infection by the fungal pathogen Botrytis cinerea, despite temporal and spatial separation between the inoculation of both microorganisms. Although Micromonospora improves plant growth and has antifungal activity against plant pathogens, the interaction between Micromonospora and AM fungi has not been studied before. Thus, the aim of the study was to work on the understanding of this interaction. The results obtained allow us to conclude that Micromonospora strains ALFpr18c and ALFb5 did not adversely affect the colonization and development of the AM fungi R. irregularis and F. mosseae on plant root. Micromonospora strain ALFpr18c increased the beneficial effect of the AM fungi on shoot dry weight of alfalfa and tomato when the AM fungi were established first on the roots. Therefore, it is possible to use Micromonospora ALFpr18c combined with AM fungi to improve plant growth. Micromonospora strains should be considered excellent plant probiotic bacteria as they combine plant growth-promoting activity with both direct antifungal activity against plant pathogens and the ability to prime plant immunity and did not adversely affect the colonization and development of the AM fungi.

Arbuscular mycorrhizal (AM) is a mutually beneficial interaction among higher plants and soil fungi of the phylum Glomeromycota. Numerous studies have pointed that jasmonic acid plays an important role in the development of the intraradical fungus. This compound belongs to a group of biologically active compounds known as oxylipins which are derived from the oxidative metabolism of polyunsaturated fatty acids. Studies of the regulatory role played by oxylipins in AM colonization have generally focused on jasmonates, while few studies exist on the 9-LOX pathway of oxylipins during AM formation. Here, the cDNA of Allene oxide synthase 3 (AOS3), a key enzyme in the 9-LOX pathway, was used in the RNA interference (RNAi) system to transform potato plants in order to suppress its expression. Results show increases in AOS3 gene expression and 9-LOX products in roots of wild type potato mycorrhizal plants. The suppression of AOS3 gene expression increases the percentage of root with mycorrhizal colonization at early stages of AM formation. AOS3 RNA interference lead to an induction of LOXA and 13-LOX genes, a reduction in AOS3 derived 9-LOX oxylipin compounds and an increase in jasmonic acid content, suggesting compensation between 9 and 13-LOX pathways. The results in a whole support the hypothesis of a regulatory role for the 9-LOX oxylipin pathway during mycorrhization., We wish to thank the Tomato Genetics Resource Centre (TGRC) of the University of California for providing tomato seeds. We would also like to thank Michael O’Shea for proof-reading the document. LC-MS/MS analyses were carried out by Dr. Lourdes Sánchez-Moreno at the Scientific Instrumentation Service of the Estación Experimental del Zaidín (CSIC), Granada, Spain. This study was supported by grants from the Comisión Interministerial de Ciencia y Tecnología (CICYT) and Fondos Europeos de Desarrollo Regional (FEDER) through the Ministerio de Economía y Competitividad in Spain (AGL2011-25930; AGL2014-52298-P) as well as the Junta de Andalucía (Research Group BIO 260). R. J. León was supported by a research fellowship from the CSIC-JAE program.

Healthy food consumption has increased the production of fruit based value-added products as a result of the awareness of their high contents of bio-active compounds like vitamins, minerals, dietary fiber and antioxidants. High moisture content in fruits can generate losses in post-harvest storage. The dehydration process based on water activity reduction, is an option for overcoming such losses. Regular hot air drying could affect negatively the quality properties of the fruit due to the long times at high temperature. Power ultrasound (US) application during the convective drying has been used as a new method to decrease drying time. The aim of this work was to evaluate the effect of the convective drying assisted by ultrasound on drying time and aroma losses of tamarillo (TS) and mango slices (MS). An experimental design was developed, showing the positive effect of ultrasound during convective drying process. Power ultrasound (20 kHz, 45 W) was applied during drying test at 50°C, applying 5 and 10 minutes of ultrasound each half hour intermittently. Weight loss of samples was measured every hour until moisture content of 10.0±1.0% (wet basis). Aroma measurement was development by SPME method. The results were compared with fresh fruit data for all tests.

a b s t r a c t A total of 150 isolates of endophytic fungi were obtained from roots of Myrtus communis grown in the Mediterranean area. Seven different endophytic fungi taxa, all belonging to the Ascomycota phylum were found. Arbuscular mycorrhizal (AM) fungi, belonging to the Glomus genus, were also present in roots of M. communis. None of the root endophytic fungi tested, except Drechslera sp., colonized the root of sorghum. Among all fungi tested, only Phoma schachtii and Cylindrocarpon destructans significantly increased the shoot dry weight of sorghum grown in sterilized soil. Phomopsis columnaris, P. schachtii, Eucasphaeria sp. and Cylindrocarpon pauciseptatum increased the dry matter of sorghum grown in unsterilized soil. The percentage of AM colonization of sorghum was increased significantly only when Ph. columnaris, P. schachtii, the two strains of Bionectria ochroleuca, Eucasphaeria sp. and C. pauciseptatum were applied to unsterilized soil. The number of CFUs of endophytic fungi inoculated in sorghum rhizosphere was similar throughout the experiment, except B. ochroleuca-1 whose population increased at the end of the experiment either in sterilized or in unsterilized soil. No significant effect of the endophytic fungi isolated from M. communis on shoot and root P, K, Ca, Na, Mg, Cu and Zn concentrations of plants grown in sterilized or unsterilized soils, except Eucasphaeria sp. which increased the shoot P concentration of sorghum grown in unsterilized soil.

Gaeumannomyces graminis var. tritici causes take-all disease, the most important root disease of cereal plants. Cereal plants are able to form a symbiotic association with soil-borne arbuscular mycorrhizal fungi which can provide bioprotection against soil-borne fungal pathogens. However, the bioprotective effect of arbuscular mycorrhizal fun gi against soil-borne fungal pathogens might vary. In the present study we tested the systemic bioprotective effect of the arbuscular mycorrhizal fungi Glomus mosseae, Glomus intraradices and Gigaspora rosea against the soilborne fungal pathogen Gaeumannomyces graminis var. tritici in a barley split-root system. Glomus intraradices, Glomus mosseae and Gigaspora rosea colonized the split-root system of barley plants at different levels; however, all arbuscular mycorrhizal fungi clearly reduced the level of root lesions due to the pathogen Gaeumannomyces graminis. Our data indicate that some arbuscular mycorrhizal fungi need high root colonization rates to protect plants against fungal pathogens, whereas others act already at low root colonization rates.

The establishment of an arbuscular mycorrhizal (AM) symbiotic interaction is a successful strategy for the promotion of substantial plant growth, development, and fitness. Numerous studies have supported the hypothesis that plant hormones play an important role in the establishment of functional AM symbiosis. Particular attention has been devoted to jasmonic acid (JA) and its derivates, which are believed to play a major role in AM symbiosis. Jasmonates belong to a diverse class of lipid metabolites known as oxylipins that include other biologically active molecules. Recent transcriptional analyses revealed up-regulation of the oxylipin pathway during AM symbiosis in mycorrhizal tomato roots and indicate a key regulatory role for oxylipins during AM symbiosis in tomato, particularly those derived from the action of 9-lipoxygenases (9-LOXs). Continuing with the tomato as a model, the spatial and temporal expression pattern of genes involved in the 9-LOX pathway during the different stages of AM formation in tomato was analysed. The effects of JA signalling pathway changes on AM fungal colonization were assessed and correlated with the modifications in the transcriptional profiles of 9-LOX genes. The up-regulation of the 9-LOX oxylipin pathway in mycorrhizal wild-type roots seems to depend on a particular degree of AM fungal colonization and is restricted to the colonized part of the roots, suggesting that these genes could play a role in controlling fungal spread in roots. In addition, the results suggest that this strategy of the plant to control AM fungi development within the roots is at least partly dependent on JA pathway activation.

The saprophytic fungi Aspergillus niger, Coriolopsis rigida, Fusarium lateritium, F. oxysporum, Mucor racemosus, Paecilomyces farinosus, Penicillium chrysogenum, P. restrictum, Trametes versicolor, Trichoderma harzianum, T. pseudokoningii and T. viride were able to decrease the growth in vitro of Verticillium dahlie in the presence of aqueous extract of olive residue. The conidia number of V. dahliae decreased when grown on aqueous extract of olive residue, autoclaved or filtered through 0.45 micron filters after culture of the fungi. These results suggest not only the predominance of suppressive substances of a biological nature, but also the existence of non-biological inhibitory substances. The olive residue decreased the negative effect of V. dahliae on shoot and root dry weight of tomato (Solanum lycopersicum L.), by the antifungal compounds present in the olive residue and by the antifungal substances produced by the antagonistic saprophytic fungi grown in this residue.

The effect of the arbuscular mycorrhizal symbiosis (AM) varies in plant cultivars. In the present study, we tested whether wild-type, old and modern tomato cultivars differ in the parameters of the AM interaction. Moreover, the bioprotective effect of AM against the soilborne tomato pathogen Fusarium oxysporum f. sp. lycopersici (Fol) was tested in the different cultivars. Ten tomato cultivars were inoculated with the arbuscular mycorrhizal fungus (AMF) Glomus mosseae alone or in combination with Fol. At the end of the experiment, AM root colonization, Fusarium infection, and the plant fresh weight was determined. The tomato cultivars differed in their susceptibility to AMF and Fol, but these differences were not cultivar age dependent. In all the cultivars affected by Fol, mycorrhization showed a bioprotective effect. Independent of the cultivar age, tomato cultivars differ in their susceptibility to AMF and Fol and the bioprotective effect of mycorrhization, indicating that the cultivar age does not affect the AM parameters tested in this study.

The systemic effect of root colonization by the arbuscular mycorrhizal fungus (AMF) Glomus mosseae on the susceptibility of old and modern barley varieties to the soil-borne fungal pathogen Gaeumannomyces graminis var. tritici (Ggt) was studied in a split-root system. Plants were precolonized on one side of the split-root system with the AMF and thereafter the other side of the split-root system was inoculated with the pathogen. At the end of the experiment the level of bioprotection was estimated by quantifying lesioned roots and the determination of the root fresh weight. AM root colonization provided protection in some of the barley genotypes tested, but not in others. This protective effect seemed to vary in the oldest and the most modern barley variety tested.

Byproducts generated from food industries, such as olive oil mills, have been studied to decrease harmful pollution and their environmental consequences. In this work, a new thermal pretreatment and saprobic fungal incubation to detoxify alperujo (two-phase olive mill waste) have been evaluated in view of its use as fertilizer in agriculture. The sequential use of both methods simplifies the thermal conditions and incubation times of the fungal treatment. Optimization of the thermal treatment from 150 to 170 °C for 45 and 15 min, respectively, reduced the incubation time with Coriolpsis rigida from 20 to 10 weeks needed to reduce phytotoxic effects on tomato plants. Therefore, the combination of thermal and biological treatments will allow the development of the potential benefits of alperujo to improve nutrients in agricultural soil., Financial support for this study was provided by the Junta de Andalucía (PO6-AGR-01906) and the Ministerio de Ciencia e Innovación (AGL2008-00572, AGL2009-12352).

We investigated the relationship between ABA and ethylene regulating the formation of the arbuscular mycorrhiza (AM) symbiosis in tomato (Solanum lycopersicum) plants and tried to define the specific roles played by each of these phytohormones in the mycorrhization process. We analysed the impact of ABA biosynthesis inhibition on mycorrhization by Glomus intraradices in transgenic tomato plants with an altered ethylene pathway. We also studied the effects on mycorrhization in sitiens plants treated with the aminoethoxyvinyl glycine hydrochloride (AVG) ethylene biosynthesis inhibitor and supplemented with ABA. In addition, the expression of plant and fungal genes involved in the mycorrhization process was studied. ABA biosynthesis inhibition qualitatively altered the parameters of mycorrhization in accordance with the plant's ethylene perception and ethylene biosynthesis abilities. Inhibition of ABA biosynthesis in wild-type plants negatively affected all the mycorrhization parameters studied, while tomato mutants impaired in ethylene synthesis only showed a reduced arbuscular abundance in mycorrhizal roots. Inhibition of ethylene synthesis in ABA-deficient sitiens plants increased the intensity of mycorrhiza development, while ABA application rescued arbuscule abundance in the root's mycorrhizal zones. The results of our study show an antagonistic interaction between ABA and ethylene, and different roles of each of the two hormones during AM formation. This suggests that a dual ethylene-dependent/ethylene-independent mechanism is involved in ABA regulation of AM formation.

We examined whether the reduced mycorrhization of abscisic acid (ABA)-deficient tomato mutants correlates with their incapacity in ABA biosynthesis and whether this effect is dependent on ethylene production. The mycorrhization of notabilis and sitiens mutants, which have different ABA deficiencies and an excess of ethylene production, was analyzed. Comparative analysis of the ABA-deficient tomato mutants showed both quantitative and qualitative differences in the pattern of arbuscular mycorrhiza (AM) colonization between the two tomato mutant phenotypes. The sitiens mutant showed a great limitation in fungal colonization (mycorrhizal intensity and arbuscule formation) well correlated with their incapacity in ABA biosynthesis. The notabilis plants, which maintained normal ABA levels in roots under our experimental conditions, appeared to be less affected in their capacity for AM formation, and only a decrease in mycorrhizal intensity was noted at the end of the mycorrhization process. Blockage of ABA formation after tungstate application resulted in a reduction in mycorrhization of wild-type tomato plants. The transcript accumulation of the mycorrhiza-responsive LePT4 gene (tomato phosphate transporter) was clearly associated with the ABA content and mycorrhiza development in roots, as the tungstate treatment in wild-type plants and the inherent ABA deficiency in sitiens mutants led to a complete abolishment of their expression. Our results suggest that the decrease in arbuscular abundance in mycorrhizal sitiens roots is directly associated with their ABA biosynthesis deficiency, and the accumulation of ethylene, as a consequence of ABA deficiency in the mutants, primarily affects mycorrhizal intensity.

Summary Pea (Pisum sativum) is an important grain legume crop whose cultivation in the Mediterranean basin and West Asia is severely constrained by infection by the weedy root parasite Orobanche crenata (crenate broomrape). Pea is a false host of other species such as O. minor, O. foetida and Phelipanche aegyptiaca. In the present experiments, we demonstrate that seed germination of the Orobanche and Phelipanche species examined is reduced in the presence of root exudates from pea plants colonised by arbuscular mycorrhizal (AM) fungi, Glomus mosseae and G. intraradices. Reduced germination was due to the effect of the AM fungi and not to the microbial populations potentially present in the soil inoculum. This protective effect of mycorrhizae was noticeable after 35 days of AM colonisation for O. crenata, O. foetida and P. aegyptiaca, but at least 45 days of colonisation were needed to get some reduction of O. minor germination.

The presence of high concentrations of arsenic (As) decreased the shoot and root dry weight, chlorophyll and P and Mg content of Eucalyptus globulus colonized with the arbuscular mycorrhizal (AM) fungi Glomus deserticola or G. claroideum, but these parameters were higher than in non-AM plants. As increased the percentage of AM length colonization and succinate dehydrogenase (SDH) activity in the root of E. globulus. Trichoderma harzianum, but not Trametes versicolor, increased the shoot and root dry weight, chlorophyll content, the percentage of AM root length colonization and SDH activity of E. globulus in presence of all As concentrations applied to soil when was inoculated together with G. claroideum. AM fungi increased shoot As and P concentration of E. globulus to higher level than the non-AM inoculated controls. The contribution of the AM and saprobe fungi to the translocation of As from root to shoot of E. globulus is discussed.

Olive oil extraction generates large amounts of olive mill residues (DOR) which may be used as fertilizer. The influence of arbuscular mycorrhizal (AM) on the phytotoxicity of dry olive residue (DOR) transformed with saprophytic fungi was studied. Aqueous extraction of DOR gave an (ADOR) fraction and an exhausted (SDOR) fraction, both of which had less phytotoxicity for tomato than the original DOR. The saprophytic fungiTrametes versicolor andPycnoporus cinnabarinus further decreased the phytotoxicity of ADOR and SDOR on tomato. The decrease of phenols concentration and the differences in the level of laccase activity caused by these fungi suggest did not account fully for the reduced phytoxicity but the fact that the higher hydrolytic enzyme activity ofP. cinnabarinus, paralleled the decrease of phytotoxicity, indicates that these enzymes seem to be involved. The AM fungusGlomus deserticola increased or exacerbated the beneficial effect of SDOR incubated with saprophytic fungi, in terms of dry weight of tomato plants. The percentage of root length colonized byG. deserticola strongly decreased in presence of DOR, but the level of mycorrhization was higher in presence of ADOR or SDOR. Our results suggest that the combination of aqueous extraction and incubation with saprophytic fungi will open the way for the use of olive oil extraction residues as organic amendment in agricultural soils.

The role of the jasmonate signalling pathway in modulating the establishment of the arbuscular mycorrhiza (AM) symbiosis between tomato plants and Glomus intraradices fungus was studied. The consequences of AM formation due to the blockage of the jasmonate signalling pathway were studied in experiments with plant mutants impaired in JA perception. The tomato jai-1 mutant (jas- monic acid insensitive 1) failed to regulate colonization and was more susceptible to fungal infection, showing acceler- ated colonization. The frequency and the intensity of fungal colonization were greatly increased in the jai-1 insensitive mutant plants. In parallel, the systemic effects on mycorrh- ization due to the activation of the jasmonate signalling pathway by foliar application of MeJA were evaluated and histochemical and molecular parameters of mycorrhizal intensity and efficiency were measured. Histochemical deter- mination of fungal infectivity and fungal alkaline phosphatase activity reveal that the systemic application of MeJA was effective in reducing mycorrhization and mainly affected fungal phosphate metabolism and arbuscule formation, ana- lyzed by the expression of GiALP and the AM-specific gene LePT4, respectively. The results of the present study clearly show that JA participates in the susceptibility of tomato to infection by arbuscular mycorrhizal fungi, and it seems that arbuscular colonization in tomato is tightly controlled by the jasmonate signalling pathway.

We studied the influence of olive mill dry residue (DOR) treated with saprobe fungi on growth of tomato and alfalfa colonized by Glomus deserticola . The application of 25 g kg −1 of dry DOR to soil decreased the shoot and root dry weight of tomato and alfalfa. Plants were more sensitive to the toxicity of DOR when colonized with the arbuscular mycorrhizal (AM) fungi. The sensitivity of both plants to the toxicity of DOR differed according to whether they were colonized by G. deserticola or by indigenous AM fungi. The phytotoxicity of DOR towards tomato and alfalfa was decreased by incubation the residue before planting with saprobe fungi for 20 wk. The beneficial effects of AM fungi on plant growth added with DOR incubated with saprobe fungi depend of the type of the plant and AM fungi. The contribution of AM fungi to the beneficial effect of DOR incubated with saprobe fungi varied according to the type of the plant and AM fungi. G. deserticola increased the shoot and root dry weight of plants when they were grown in the presence of DOR incubated with saprobe fungi for 20 wk. The beneficial effect of saprobe fungi on the dry weight and the level of AM mycorrhization of plants seem to be related to the decrease caused by these fungi in the phenol concentration in DOR. However, the toxicity of DOR due to substances other than phenols can not be ignored. The use of certain saprobe and AM fungi allows the possibility of using DOR as an organic fertilizer.

The present study mainly investigated the ability of solid-state cultures of the non-pathogenic Fusarium oxysporum strain BAFC 738 to transform aromatic components to reduce the phytotoxicity in olive-mill dry residue (DOR), the waste from the two-phase manufacturing process. Lignin, hemicellulose, fats and water-soluble extractives contents of DOR colonized by the fungus for 20 weeks were reduced by 16%, 25%, 71% and 13%, respectively, while the cellulose content increased by 25%. In addition, the ethyl acetate-extractable phenolic fraction of the waste was reduced by 65%. However, mass-balance ultra-filtration and size-exclusion chromatography experiments suggested that the apparent removal of that fraction, mainly including 2-(3,4-dihydroxyphenyl)ethyl alcohol and 2-(4-hydroxyphenyl)ethyl alcohol, was due to polymerization. Mn-peroxidase and Mn-independent peroxidase activities were found in F. oxysporum solid-state cultures, while laccase and aryl alcohol oxidase activities were not detected. Tests performed with seedlings of tomato (Lycopersicum esculentum L.), soybean (Glycine maximum Merr.), and alfalfa (Medicago sativa L.) grown on soils containing 6% (w/w) of bioconverted DOR (kg soil)(-1) showed that the waste's phytotoxicity was removed by 20 weeks-old fungal cultures. By contrast, the same material exhibited a high residual toxicity towards lettuce (Lactuca sativa L.).

No clear data are available on how flavonoids from different chemical groups affect root colonization by arbuscular mycorrhizal fungi (AMF) and whether flavonoids affecting the presymbiotic growth of AMF also affect root colonization by AMF. In the present work, we compared the effect of flavones (chrysin and luteolin) and flavonols (kaempferol, morin, isorhamnetin, and rutin) on root colonization (number of entry points and degree of root colonization) of tomato plants ( Lycopersicum esculentum L.) with the effect of these flavonoids on the presymbiotic growth of these AMF, which has been reported in a recent study. With all tested AMF ( Gigaspora rosea , Gigaspora margarita , Glomus mosseae, and Glomus intraradices) a correlation between the number of entry points and the percentage of root colonization was found. When the number of entry points was high, root colonization was also enhanced. Application of the flavones chrysin and luteolin and of the flavonol morin increased the number of entry points and the degree of colonization,whereas the flavonols kaempferol, isorhamnetin, and rutin showed no effect. These results show that in contrast to their effect on the presymbiotic growth of the AMF on the level of root colonization, the tested flavonoids do not exhibit a genus- and species-specificity. Moreover, comparison of our data with the data obtained by J.M. Scervino, M.A. Ponce, R. Erra-Bassells, H. Vierheilig, J.A. Ocampo, and A. Godeas. (2005a. J. Plant Interact. 15: 22–30) indicates that a positive effect on the hyphal growth of AMF does not necessarily result in an enhanced AM root colonization, further indicating that the mode of action of flavonoids at the level of root colonization is more complex.

The role of abscisic acid (ABA) during the establishment of the arbuscular mycorrhiza (AM) was studied using ABA sitiens tomato (Lycopersicon esculentum) mutants with reduced ABA concentrations. Sitiens plants and wild-type (WT) plants were colonized by Glomus intraradices. Trypan blue and alkaline phosphatase histochemical staining procedures were used to determine both root colonization and fungal efficiency. Exogenous ABA and silver thiosulfate (STS) were applied to establish the role of ABA and putative antagonistic cross-talk between ABA and ethylene during AM formation, respectively. Sitiens plants were less susceptible to the AM fungus than WT plants. Microscopic observations and arbuscule quantification showed differences in arbuscule morphology between WT and sitiens plants. Both ABA and STS increased susceptibility to the AM fungus in WT and sitiens plants. Fungal alkaline phosphate activity in sitiens mutants was completely restored by ABA application. * The results demonstrate that ABA contributes to the susceptibility of tomato to infection by AM fungi, and that it seems to play an important role in the development of the complete arbuscule and its functionality. Ethylene perception is crucial to AM regulation, and the impairment of mycorrhiza development in ABA-deficient plants is at least partly attributable to ethylene.

The mycorrhizal association with the boojum tree, Fouquieria columnaris (=Idria columnaris), was studied. This unusual tree is almost exclusively endemic to granite and volcanic soils in highly arid areas of the Baja California Peninsula of Mexico. Soil and root samples from ten sites, covering the extent of geographic distribution of the tree on the peninsula, were analyzed. The roots of the boojum tree contained all structures of an arbuscular mycorrhizal (AM) association. Morphologically different species, 23 in number, were identified in close vicinity to the boojum tree indicating that F. columnaris is associated with a high number of AM species of several AM genera and families.

Aluminum in acidic conditions is toxic to plants. Aluminum tolerance in some plant species has been ascribed to arbuscular mycorrhizal fungal symbiosis. In this study, the application of aluminum was found to inhibit mycelia development of saprobe fungi Fusarium concolor and Trichoderma koningii and the hyphal length of the arbuscular mycorrhizal fungi Glomus mosseae and Glomus deserticola in vitro. Several levels of aluminum were applied to Eucalyptus globulus plants and inoculated with arbuscular mycorrhizal fungi alone or together with both saprobe fungi. The application of 1,500 mg kg−1 decreased the shoot and root dry weight, chlorophyll content and total P, Mg, and Ca concentrations in the shoot of E. globulus. However, both mycorrhizal fungi G. mosseae and G. deserticola inoculated alone increased the shoot dry weight of Eucalyptus, compared with a non- arbuscular mycorrhizal inoculated control treated with 1,500 mg kg−1 of aluminum. When 1,500 mg kg−1 of aluminum was applied, T. koningii increased the effect of G. deserticola on the shoot weight of eucalyptus, whereas with 3,000 mg kg−1, shoot weight and arbuscular mycorrhizal colonization decreased in all treatments. With 1,500 mg kg−1, the highest accumulation of aluminum in the shoot was obtained when G. deserticola was inoculated together with T. koningii. The possibility of manipulating an arbuscular mycorrhizal inoculation together with a saprobe fungus confers a high aluminum resistance in E. globulus. The effect of such combined inoculation is particularly important in some Chilean volcanic acid soils, mainly those which have been intensively cropped and are without lime addition, which facilitates the increase of phytotoxic aluminum species and limits their agricultural use. Therefore, such dual inoculation in field conditions deserves further investigation. Overall, the arbuscular mycorrhizal and saprobe fungi contribute to the increase in resistance of E. globulus to aluminium.

Dry olive mill residue (DOR) is a solid waste arising from the olive oil two-phase extraction system. The objective of the present study was to investigate the impact of an aerobic treatment of DOR with selected lignin-degrading fungi on both organic matter evolution and residual phytotoxicity of the waste. To this aim, several white-rot fungi, including Phlebia radiata, Coriolopsis rigida, Phanerochaete chrysosporium, Pycnoporus cinnabarinus, Poria subvermispora and Pleurotus pulmonarius were inoculated under axenic conditions for 2 and 20 weeks. The chemical composition and phytotoxicity of DOR were scarcely affected by fungi after 2 weeks incubation. By contrast, both a significant depletion of phenolic compounds and a partial removal of phytoxicity towards Lycopersicum esculentum plants were generally obtained after 20 weeks. The most effective fungus in degrading lignin, total phenols and in removing phytotoxicity was C. rigida. A high correlation was observed between phytotoxicity and phenols added to soil with the waste.

We studied the influence of the laccase activity of two white-rot fungi on the toxic effect of water-soluble substances from dry residues of olives (ADOR) on tomato plants. Pycnoporus cinnabarinus and Coriolopsis rigida decreased the phenol content of ADOR to 73% after 15 days. P. cinnabarinus and C. rigida produced laccase activity after 5 and 15 days, respectively, and the highest activity in both fungi was detected at 20 days. The treatment of ADOR with these white-rot fungi decreased the phytotoxicity of this residue on tomato plants. A close relationship was found between the amount of laccase produced, the decrease in phenol content of ADOR by the saprobic fungi, decrease of phytotoxicity of ADOR, and the increase in dry weight of tomato plants. These results show that phenol removal by the laccase activity of white-rot fungi can be important in the elimination of phytotoxic substances present in olive-mill dry residues.

The effect of different concentrations (0.5, 2 and 8mM) of apigenin and its glycosidated form 5,7,4 0 -hydroxy flavone glycoside on arbuscular mycorrhizal (AM) fungal spore germination, hyphal growth, hyphal branching, the formation of entry points and root colonization of Gigaspora. rosea, Gi. margarita, Glomus mosseae and G. intraradices was tested. The lowest apigenin concentration (0.5mM) nearly doubled hyphal branching, the formation of entry points and root colonization of all four tested fungi, whereas higher concentrations (2 and 8mM) nearly doubled the hyphal growth of Gi. margarita, G. mosseae and G. intraradices. In none of the treatments with the apigenin-glycoside any effect on AM fungi could be observed. Our data show that apigenin exhibits an AM fungal genus and even species activity and we provide strong evidence that glycosidation results in a loss of its activity towards AM fungi. r 2006 Elsevier Ltd. All rights reserved.

Two strains of Gluconacetobacter diazotrophicus (Pal 5, UAP5541) and the arbuscular mycorrhizal fungus Glomus intraradices increased both the shoot and root dry weight of sorghum 45 days after inoculation, whereas they had no effect on the shoot and root dry weight of maize. Co-inoculation (Gluconacetobacter diazotrophicus plus Glomus mosseae) did not increase the shoot and root dry weight of either plant. There was a synergistic effect of Gluconacetobacter diazotrophicus on root colonization of maize by Glomus intraradices, whereas an antagonistic interaction was observed in the sorghum root where the number of Gluconacetobacter diazotrophicus and the colonization by Glomus intraradices were reduced. Plant roots inoculated with Gluconacetobacter diazotrophicus and Glomus intraradices, either separately or together, significantly increased root endoglucanase, endopolymethylgalacturonase and endoxyloglucanase activities. The increase varied according to the plant. For example, in comparison with non-inoculated plants, there were higher endoglucanase (+328%), endopolymethylgalacturonase (+180%) and endoxyloglucanase (+125%) activities in 45-day old co-inoculated maize, but not in 45-day old sorghum. The possibility is discussed that hydrolytic enzyme activities were increased as a result of inoculation with Gluconacetobacter diazotrophicus, considering this to be one of the mechanisms by which these bacteria may increase root colonization by AM fungi.

The application of Pb inhibited the development of mycelia of the saprobe fungi Fusarium concolor and Trichoderma koningii and the hyphal length of the arbuscular mycorrhizal fungi (AM) Glomus mosseae and G. deserticola in vitro. The application to soil of 1500 mg kg−1 of Pb decreases the dry weight, total N, P, Mg and Fe concentration and chlorophyll content of the shoot of E. globulus no inoculated with AM fungi. However, G. deserticola increased the dry weight, total nutrient concentration and chlorophyll content of the shoot, and the percentage of AM root length colonization and the succinate dehydrogenase activity of AM mycelia of E. globulus in presence of 1500 mg kg−1 of Pb, and these increases were higher when G. deserticola was inoculated together with T. koningii. The application to soil of 3000 mg kg−1 of Pb decreased the shoot dry weight and AM colonization of E. globulus in all treatments tested. Pb was accumulated in the stem more than in the leaves of E. globulus. In presence of 1500 mg kg−1 of Pb the highest accumulation of this metal in the stem took place when E. globulus was colonized with G. deserticola. In conclusion, the possibility to increase Lead accumulation in stem is very attractive for phytoextraction function, the saprobe fungi, AM and their interaction may have a potential role in elevating phytoextraction efficiency and stimulate plant growth under adverse conditions such as lead contaminated soil.

The effect of flavonoids isolated from arbuscular mycorrhizal (AM) colonized and noncolonized clover roots on the number of entry points and percentage of root colonization of tomato (Lycopersicum esculentum L.) by Gigaspora rosea, Gi margarita, Glomus mosseae and G. intrarradices symbionts was determined. With fungi of both genera, a correlation between the number of entry points and the percentage of root colonization was found in the presence of some of the tested flavonoids. The flavonoids acacetin and rhamnetin, present in AM clover roots, inhibited the formation of AM penetration structures and the AM colonization of tomato roots, whereas the flavonoid 5,6,7,8,9-hydroxy chalcone, which could not be detected in AM clover root, inhibited both parameters. The flavonoid quercetin, which was present in AM clover roots, stimulated the penetration and root colonization of tomato by Gigaspora. However, the flavonoids 5,6,7,8-hydroxy-4'-methoxy flavone and 3,5,6,7,4'-hydroxy flavone, which was not found in AM clover root, increased the number of entry points and the AM colonization of tomato roots by Gigaspora. These results indicated that flavonoids could be imnplicated in the process of regulation of AM colonization in plant root, but its role is highly complex and depend not only on flavonoids, but also on AM fungal genus or even species.